Did you have fun reading the USB audio spec stu? What a document that one is! I've just had the misfortune of reading it as I've just added a "PC interface" to our doppler radar (aka speed detector) interface and decided the nicest way of doing it was to pass the "doppler audio" straight into the "PC".

All I can say is that I'm glad that they include sample descriptors in the usb audio document otherwise I think I'd still be trying to decipher what exactly is needed in them!